A stenosis, or narrowing of a blood vessel such as an artery may comprise a hard, calcified substance and/or a softer thrombus (clot) material. There have been numerous therapeutic procedures developed for the treatment of stenosis in an artery. One of the better-known procedures is percutaneous transluminal coronary angioplasty (PTCA). According to this procedure, the narrowing in the coronary artery can be reduced by positioning a dilatation balloon across the stenosis and inflating the balloon to re-establish acceptable blood flow through the artery. Additional therapeutic procedures may include stent deployment, atherectomy, and thrombectomy, which are well known and have proven effective in the treatment of such stenotic lesions. Distal occlusion or filtration, with or without aspiration embolectomy, have also been developed to prevent downstream embolization by collecting and removing atheroembolic debris that may be generated during any of the above therapies. Increasingly specialized aspiration catheters have been developed for aspiration of body fluids contaminated with thrombus or embolic debris before, during and/or after an arterial intervention.
One important feature of aspiration catheters is the ability to rapidly and efficiently aspirate large embolic particles without the need to first break them into smaller sub-particles. This advantage is achieved, at least in part, by providing the catheter with an aspiration lumen and aspiration lumen inlet port having as large a cross sectional area as possible, given overall size constraints of the catheter design. However, one drawback to aspiration catheters is that the aspiration lumen opening has a fixed cross sectional area that is unable to increase in size to accommodate larger embolic particles.
Another important feature of aspiration catheters is the tip. Current aspiration catheters have distal tips that have fixed geometry, viz., the tips are either orthogonal or oblique with respect to a longitudinal axis of the catheter. Orthogonal tips are well suited for fully contacting a clot to be aspirated and for aspirating material directly in front of the tip. However, orthogonal tips are not well suited for aspirating material positioned at a side of the aspiration catheter or thrombus adhering to the vessel wall. Oblique tips provide an angled opening suitable for aspirating particles positioned at a side of the aspiration catheter and can improve the removal of thrombus adhering to the vessel wall. However, oblique tips are not well suited for fully contacting a clot directly in front of the tip. Thus, with prior devices having either an orthogonal tip or an oblique tip, a practitioner does not have an aspiration catheter suitable for aspirating particles both in front of aspiration opening and to the side of the opening.
Consequently, a need exists for aspiration catheters that overcome these and other disadvantages.